Given the recent discussions here and elsewhere about the suitability (or lack thereof) of globally averaged surface temperature as a measure of anthropogenic climate change, I note a paper by Swiss climate researcher Rolf Philipona and colleagues that found a positive water vapor feedback responsible for excess warming in Europe:
Unexpected large temperature and humidity rises over the past two decades were recently observed in central Europe. While increasing temperature and absolute humidity are consistent with measured surface radiative forcings (changes of radiative fluxes over time), they are two to three times larger than predicted by general circulation models (GCM) . The main question therefore is, whether the rapid increases are in fact heightened by positive water
Warning, spoiler ahead! Don’t read on if you’re going to see the movie!
Their answer is yes – they see rapid increases being heightened by positive water vapor feedback
In fact, Eastern Europe has seen increases of as much as 2 degrees C per decade of late, they say. The culprit is water vapor, which is a strong greenhouse gas. Warmer temperatures as a result of human-emitted greenhouse gases cause evaporation, essentially, pushing more water vapor into the atmosphere which then amplifies the warming.
If I may borrow a phrase from Roger Pielke Sr., this is “more evidence on the spatial complexity of climate forcings” and more evidence of why a single global number misses a lot of what’s really important.